This invention relates to an apparatus for forming images of items advanced in an organized or random manner on one or several conveyors. The apparatus has at least one illuminating unit and at least one image-capturing unit (camera) associated with the illuminating unit. The image-capturing unit forms images of the items on the conveyor. The apparatus further includes a control device which controls the illuminating and image-capturing units, for example, in a manner as described in U.S. Pat. Nos. 4,972,093 and 5,936,353.
An apparatus of the above-outlined type is disclosed in European Patent No. 0 856 465 which does not describe any specific illuminating device. An illumination by environmental light has the disadvantage that the reception of the line camera described in the patent may be adversely affected by interfering environmental light effects and thus the article-manipulating gripper devices cannot be accurately controlled.
Conventional illuminating devices have the additional disadvantage that their light sources radiate heat which may lead to a deterioration of the item quality, particularly in case of heat sensitive items such as food products, particularly chocolate or glazed items.